There's some evidence that there is a limit to the rate at which body fat can be oxidized. If your calorie deficit is greater than that, you may just be losing lean mass. And there are not many situations where you want that to happen.

A limit on the maximum energy transfer rate from the human fat store in hypophagia is deduced from experimental data of underfed subjects maintaining moderate activity levels and is found to have a value of (290+/-25) kJ/kgd. A dietary restriction which exceeds the limited capability of the fat store to compensate for the energy deficiency results in an immediate decrease in the fat free mass (FFM). In cases of a less severe dietary deficiency, the FFM will not be depleted.

You'll note that this applied to people with a moderate activity level. With a structured resistance training program and more dietary protein, a larger calorie deficit might be possible. But 31cal/lb/day is kind of a lot.

Example:Take a 250lb man with 33% body fat. He has 83.3 lbs of fat.He may be able to sustain a daily deficit of up to 2580 calories without losing muscle. Now, this will be less than ideal for other reasons, many of them mental. He'd also likely be left with a much slower metabolism by the time he is done dieting, than if he had gone slower. But on a short-term basis, it wouldn't necessarily be counterproductive.

It's certainly not the case that faster is always better. You need certain minimums of dietary protein, fats, and micronutrients in order to function properly. Whether or not you're losing body fat or lean mass, you don't want to build nutrient deficiencies into your diet. And the more aggressive your calorie deficit, the more you risk binging, jeopardize dietary adherence, and invite adverse effects on your health and endocrine system in particular.

Sacre bleu, that all sounds jolly complicated. As a 5'6 woman I work on a 1000 calorie-a-day intake and that seems to work, plus I don't generally feel too hungry. No doubt someone'll tell me there's something wrong with it BUT I'm eating a good mix of whole, natural foods, feeling good and losing the weight so I'll keep at it whilst it works! Having tried most types of programmes I find this the most flexible with the least disadvantages.... Good luck!

I try to maintain a 1,000 calorie a day deficit. That means I eat more when I work harder, and less when I'm more sedentary. Mike is right, there's much more to it than calories in vs. calories out, but to the lay fat person like me, that simple equation has been mighty successful. And so has the reverse, when I stopped counting and stopped working hard, I gained. Most importantly, though, it's good for me mentally and spurs me to pay attention to both prongs of the healthy-living midset: eat well, move around.

"The grass ain't greener, the wine ain't sweeter, either side of the hill" The Grateful Dead

The 3 main things that are important to loose weight. Is BMI, your Protein intake, & resting metabalic rate. I would be glad to help you formualate all of this based on your weight, height, etc! No one should EVER eat less than 1,000 calories a day! Remember it is MUSCLE that burns FAT even @ rest so eat protein to keep your muscle and loose FAT!BMI: BMI, or Body Mass Index, is a measurement that uses a scientific formula to determine a person's safest, healthiest weight based upon their weight and height.Protein Factor: Protein Factor is a calculation used to determine your optimum calorie or protein intake for weight loss.Resting Metabolic Rate (RMR): The number of calories one burns at rest during a 24-hour period.

If your a MAN 5'7 277pounds. your BMI is 43, you need to intake at least 167 g of protein per day. your RMR would be 2305 so eat less than that (1600 - 1900) a day if your sedimentary. Best of luck!

Thanks everyone! Your kind replies this make a massive amount of sense. On my last diet, I managed to lose 100lb in six months and then managed to put 110lb back on in under two years and felt that I was not particularly overeating. The diet I used was one from Lighter Life which restricts intake to under 500 calories a day. Obviously after 6 months my metabolic rate had slowed down to such an extent that weight gain even at a "normalish" daily calorie intake was inevitable.

I have recently calculated that during my dieting "career" over the years I have lost in access of 500lb, I really don't feel I can do it again so this really does need to be the last time I lose the weight. It is therefore imperative I find a way to lose it for good.

It seems logical that the whole concept of a diet is flawed, if a dieter sets a goal and achieves it, naturally the diet is then over. On the return to the life "Before Diet" due to metabolic rates being so low, weight is quickly piled back on. It seems then that the slower the weigh loss the better for a permanent solution.

ButterflyDye, thanks so much for your help. As you can see I am now 277lb after losing 17lb in my first ten days. I am just under 5'7" and although I am in the bicycle trade my life is mainly spent working at my desk. I work from home so the journey to work is literally 100yds to the end of the garden to my office and back daily, with the odd bit of shopping at the weekend. I was always very fit until my late twenties working-out, running or playing squash every week day, and sailing/windsurfing competitively at the weekends. Everything went south when I started my first business!

Over the last 13 days I have averaged less than 1000 calories, it seems I should be aiming for 1600. I will have a go and let you know how it goes!

There is a lot of talk at the moment about fasting for two unconsecutive days a week, would this be beneficial whilst controlling calories to 1600 on the other five days?

It is never recomended to FAST. For then you end up loosing muscle mass. It is our muscle that burns fat and calories.If you can document your food and work out on this site (fat secret)you will begin to see that ever 4000 calories adds up to you loosing 1 pound of weight. It is heathy and helps you keep off the weight if you loose less than 3 pounds a week. If you loose more than 10 pounds in a month the weight will return quickly. Try to eat PROTEIN to keep your muscle and turn your FAT into Muscle. Make sure you never eat less than 1000 cal a day. Less than that and you will loose hair, and become very unhealthy...on the inside and out.Your BMI is around 45. It is a wise thing that you are once again choosing a healthier life style. Remember you don't want a DIET you want A NEW WAY OF LIFE!! You need 171 g of protein a day to keep your muscle. It is very difficult for a person to get that much protein. You will need some protein supplements. I love a protein shake w/ an extra scoop of protein powder. You burn 2357 cal just resting every day. If you were to keep your intake to 1300 a day you will be loosing a pound and a half a week! That is perfect to help you be healthy and keep the weight off.Best of Luck

I am a woman under 5'5" and weigh about 256...I too have had the wondrous pleasure of trying every DIET in the book! I have found though that DIETING never works when you focus on the fact it is only for a short while then you can go back to what you were eating before you started! In fact the word "diet" has the word DIE in it and who wants to die without the foods they love? So this is what I have discovered along the way. Your body in prehistoric times would go through lean months and fat months depending on the supply of foods through the summer and winter months. It was common for men and women to shed weight during the summer only to put it on during the winter. So in order to prevent your body from doing the same thing, you need to excersize excercize and NEVER starve yourself by limiting the amount of calories you take in but yet EAT when you excersize. I found that I just couldn't take enough calories in and when I did that I would plateau but when I had the right amount of calories versus my excersize I was dropping the weight like crazy. My problem is I am simply addicted to candy and ice cream and although once in a while is ok it isn't ok to eat the WHOLE bag in one sitting or the whole tub of ice cream. So good luck on your journey to a fitter you!

Yes. Yes there is. Try to maintain 500-1000 calories deficit daily. Try to find out how many calories you actually burn daily, including exercise, and go with 500-1000 calories less. This is the "sweet spot" for most people - where the body is happy to shed some fat.

Of course, there are other factors, like how high your body fat percentage is. I believe that the less you have to lose, the smaller the deficit in general. Of course this will also slow down the weight loss, but it will ENSURE the weight loss.

"Losing weight is never about eating as little as possible"- Kingkeld."You wouldn't worry so much about what others think of you if you realized how seldom they do.― Eleanor Roosevelt"Do. Or do not. There is no trying."- Master Yoda.

I went from morbidly obese to being the owner of TABDIG - a weight loss coaching service that helps people worldwide losing weight. It's been an amazing journey. From October 4th 2010 to April 3rd 2012 I lost half my body weight - 80 kilos/170 lbs. Since then, I have had two cosmetic surgeries to remove excess skin. I have now quadrupled my strength, gained several kilos in muscle mass, and today I focus on building muscle, optimizing my diet, living healthy and helping people to reach the very same goals. I am stronger, healthier, thinner, happier! If you feel that you need help losing weight, don't hesitate to send me an inbox message.

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